Turning fresh water tank into gray water tank

I brought this up a few years back, but can't find the thread. Not sure if it had the title I wanted anyway, so decided to start a new one.

Has anyone ever done this?

We never boondock and don't care about resale value. This is something that has been in the back of my mind since we owned the camper. Just that empty tank sitting there, while we drag around a 32 gallon tote. I feel like there must be a way to utilize it for gray water.

We never boon dock either. Thought about looking into this mod. But after being under my camper my fresh water tank is behind the axle and both shower and sink drain are in front of axle. If we were going to be camping for more than a couple of days we would still need to drain the tank into the tote, this seem just like double work to me as we use our shower every evening. I did however move the shower drain to the left side of camper and put a 3 inch RV connector for if we ever get a site with sewer hookups, did not like having the tote under awning where the shower drain was originally located by manufacture.

For me it would be less convenient. I have both a 20 gal fresh tank and a 20 gal gray tank plumbed to the shower only. I will be the first to admit - I am not the most frugal when it comes to water. Since I camp exclusively with hookups it is not that much of an issue. However, with heavy dish washing, hand washing and brushing teeth and other things I can fill up my 25 gal tote pretty quick. I would be most peeved if I had to break camp because I filled up my gray tank.

That being said, on mine I do have a drain petcock like everyone else. I suppose you could swap the petcock for a full flow valve, but that will take a while to drain 20 gal through a garden hose. You would need to cut into the tank and install some piping and a waste valve. However - you may be too low under the chassis at that point. My pup sits pretty low, and I would be concerned about damage in transit. My gray water tank does have a waste valve, but it is the smaller 1 1/4" size. I have never used it though, and half the handle is missing sue to a prior owners mishap with dirt roads.